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author | Peter Collingbourne <peter@pcc.me.uk> | 2014-03-06 04:11:10 +0000 |
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committer | Peter Collingbourne <peter@pcc.me.uk> | 2014-03-06 04:11:10 +0000 |
commit | 9d3d032c7d9686fbd31c776f65155367d3e19dcd (patch) | |
tree | dfb6ea0eaf82829a0ec28c269c3c849febe952b4 | |
parent | 48c74700ec233e7b9ac0c1f06215cd443424cb62 (diff) | |
download | libcxx_35a-9d3d032c7d9686fbd31c776f65155367d3e19dcd.tar.gz |
Do not derive __gnu_cxx::hash<T> from std::hash<T>.
Instead, define explicit specializations for the basic types listed in
the SGI documentation. This solves two problems:
1) Helps avoid silent ODR violations caused by the absence of a
user-supplied __gnu_cxx::hash specialization in cases where a std::hash
specialization exists (e.g. for std::string).
2) __gnu_cxx::hash semantics are slightly different to those of
std::hash (for example, the former may dereference a pointer argument)
so it is inappropriate for __gnu_cxx::hash to receive std::hash
specializations by default.
Differential Revision: http://llvm-reviews.chandlerc.com/D2747
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@203070 91177308-0d34-0410-b5e6-96231b3b80d8
-rw-r--r-- | include/ext/__hash | 93 | ||||
-rw-r--r-- | test/extensions/hash/specializations.fail.cpp | 17 | ||||
-rw-r--r-- | test/extensions/hash/specializations.pass.cpp | 29 | ||||
-rw-r--r-- | test/extensions/nothing_to_do.pass.cpp | 12 |
4 files changed, 149 insertions, 2 deletions
diff --git a/include/ext/__hash b/include/ext/__hash index c0523cce..5675d540 100644 --- a/include/ext/__hash +++ b/include/ext/__hash @@ -19,8 +19,7 @@ namespace __gnu_cxx { using namespace std; -template <typename _Tp> struct _LIBCPP_TYPE_VIS_ONLY hash : public std::hash<_Tp> - { }; +template <typename _Tp> struct _LIBCPP_TYPE_VIS_ONLY hash { }; template <> struct _LIBCPP_TYPE_VIS_ONLY hash<const char*> : public unary_function<const char*, size_t> @@ -41,6 +40,96 @@ template <> struct _LIBCPP_TYPE_VIS_ONLY hash<char *> return __do_string_hash<const char *>(__c, __c + strlen(__c)); } }; + +template <> struct _LIBCPP_TYPE_VIS_ONLY hash<char> + : public unary_function<char, size_t> +{ + _LIBCPP_INLINE_VISIBILITY + size_t operator()(char __c) const _NOEXCEPT + { + return __c; + } +}; + +template <> struct _LIBCPP_TYPE_VIS_ONLY hash<signed char> + : public unary_function<signed char, size_t> +{ + _LIBCPP_INLINE_VISIBILITY + size_t operator()(signed char __c) const _NOEXCEPT + { + return __c; + } +}; + +template <> struct _LIBCPP_TYPE_VIS_ONLY hash<unsigned char> + : public unary_function<unsigned char, size_t> +{ + _LIBCPP_INLINE_VISIBILITY + size_t operator()(unsigned char __c) const _NOEXCEPT + { + return __c; + } +}; + +template <> struct _LIBCPP_TYPE_VIS_ONLY hash<short> + : public unary_function<short, size_t> +{ + _LIBCPP_INLINE_VISIBILITY + size_t operator()(short __c) const _NOEXCEPT + { + return __c; + } +}; + +template <> struct _LIBCPP_TYPE_VIS_ONLY hash<unsigned short> + : public unary_function<unsigned short, size_t> +{ + _LIBCPP_INLINE_VISIBILITY + size_t operator()(unsigned short __c) const _NOEXCEPT + { + return __c; + } +}; + +template <> struct _LIBCPP_TYPE_VIS_ONLY hash<int> + : public unary_function<int, size_t> +{ + _LIBCPP_INLINE_VISIBILITY + size_t operator()(int __c) const _NOEXCEPT + { + return __c; + } +}; + +template <> struct _LIBCPP_TYPE_VIS_ONLY hash<unsigned int> + : public unary_function<unsigned int, size_t> +{ + _LIBCPP_INLINE_VISIBILITY + size_t operator()(unsigned int __c) const _NOEXCEPT + { + return __c; + } +}; + +template <> struct _LIBCPP_TYPE_VIS_ONLY hash<long> + : public unary_function<long, size_t> +{ + _LIBCPP_INLINE_VISIBILITY + size_t operator()(long __c) const _NOEXCEPT + { + return __c; + } +}; + +template <> struct _LIBCPP_TYPE_VIS_ONLY hash<unsigned long> + : public unary_function<unsigned long, size_t> +{ + _LIBCPP_INLINE_VISIBILITY + size_t operator()(unsigned long __c) const _NOEXCEPT + { + return __c; + } +}; } #endif // _LIBCPP_EXT_HASH diff --git a/test/extensions/hash/specializations.fail.cpp b/test/extensions/hash/specializations.fail.cpp new file mode 100644 index 00000000..8eeffb58 --- /dev/null +++ b/test/extensions/hash/specializations.fail.cpp @@ -0,0 +1,17 @@ +//===----------------------------------------------------------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is dual licensed under the MIT and the University of Illinois Open +// Source Licenses. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// + +#include <assert.h> +#include <ext/hash_map> +#include <string> + +int main() +{ + assert(__gnu_cxx::hash<std::string>()(std::string()) == 0); // error +} diff --git a/test/extensions/hash/specializations.pass.cpp b/test/extensions/hash/specializations.pass.cpp new file mode 100644 index 00000000..884614ec --- /dev/null +++ b/test/extensions/hash/specializations.pass.cpp @@ -0,0 +1,29 @@ +//===----------------------------------------------------------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is dual licensed under the MIT and the University of Illinois Open +// Source Licenses. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// + +#include <assert.h> +#include <ext/hash_map> +#include <string> + +int main() +{ + char str[] = "test"; + assert(__gnu_cxx::hash<const char *>()("test") == + std::hash<std::string>()("test")); + assert(__gnu_cxx::hash<char *>()(str) == std::hash<std::string>()("test")); + assert(__gnu_cxx::hash<char>()(42) == 42); + assert(__gnu_cxx::hash<signed char>()(42) == 42); + assert(__gnu_cxx::hash<unsigned char>()(42) == 42); + assert(__gnu_cxx::hash<short>()(42) == 42); + assert(__gnu_cxx::hash<unsigned short>()(42) == 42); + assert(__gnu_cxx::hash<int>()(42) == 42); + assert(__gnu_cxx::hash<unsigned int>()(42) == 42); + assert(__gnu_cxx::hash<long>()(42) == 42); + assert(__gnu_cxx::hash<unsigned long>()(42) == 42); +} diff --git a/test/extensions/nothing_to_do.pass.cpp b/test/extensions/nothing_to_do.pass.cpp new file mode 100644 index 00000000..b58f5c55 --- /dev/null +++ b/test/extensions/nothing_to_do.pass.cpp @@ -0,0 +1,12 @@ +//===----------------------------------------------------------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is dual licensed under the MIT and the University of Illinois Open +// Source Licenses. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// + +int main() +{ +} |